Qt: Support versions < 5.6

Source/Core/DolphinQt2/QtUtils/ActionHelper.h

@@ -0,0 +1,22 @@
+// Copyright 2017 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <QAction>
+#include <QKeySequence>
+#include <QString>
+
+// Since we have to support Qt < 5.6, we need our own implementation of addAction(QString&
+// text,QObject*,PointerToMemberFunction);
+template <typename ParentClass, typename RecieverClass, typename Func>
+QAction* AddAction(ParentClass* parent, const QString& text, const RecieverClass* receiver,
+                   Func slot, const QKeySequence& shortcut = 0)
+{
+  QAction* action = parent->addAction(text);
+  action->setShortcut(shortcut);
+  action->connect(action, &QAction::triggered, receiver, slot);
+
+  return action;
+}